Light emitting devices including a quantum dot color conversion material and method of making thereof

Abstract

A method of forming a light emitting device includes providing a free standing support containing a matrix material including first and second vias, depositing in the first vias a first photocurable quantum dot ink including first quantum dots suspended in a first photocurable polymer, illuminating the first photocurable quantum dot ink with ultraviolet radiation or blue light from first LEDs of an array of LEDs to crosslink the first photocurable polymer material in the first vias, depositing in the second vias a second photocurable quantum dot ink comprising second quantum dots suspended in a second photocurable polymer material, illuminating the second photocurable quantum dot ink with ultraviolet radiation or blue light from second LEDs of the array of LEDs to crosslink the second photocurable polymer material in the second vias, and attaching the free standing support to the array of LEDs after the illuminating.

What is claimed is: 
     
         1 . A method of forming a light emitting device, comprising:
 providing a free standing support comprising a matrix material containing first and second vias;   depositing in the first vias in the matrix material a first photocurable quantum dot ink comprising a first plurality of quantum dots suspended in a first photocurable polymer material;   illuminating the first photocurable quantum dot ink with ultraviolet radiation or blue light from first light emitting diodes of an array of light emitting diodes to crosslink the first photocurable polymer material in the first vias;   depositing in the second vias in the matrix material a second photocurable quantum dot ink comprising a second plurality of quantum dots suspended in a second photocurable polymer material, wherein the second plurality of quantum dots are configured to emit light of a different peak wavelength than the first plurality of quantum dots;   illuminating the second photocurable quantum dot ink with ultraviolet radiation or blue light from second light emitting diodes of the array of light emitting diodes to crosslink the second photocurable polymer material in the second vias: and   attaching the free standing support to the array of light emitting diodes after the steps of illuminating the first and the second photocurable quantum dot ink.   
     
     
         2 . The method of  claim 1 , wherein the matrix material further comprises third vias. 
     
     
         3 . The method of  claim 2 , further comprising:
 depositing in the third vias in the matrix material third photocurable quantum dot ink comprising third plurality of quantum dots suspended in a third photocurable polymer material, wherein the third plurality of quantum dots are configured to emit light of a different peak wavelength than the first and the second plurality of quantum dots; and   illuminating the third photocurable quantum dot ink with ultraviolet radiation or blue light from third light emitting diodes of the array of light emitting diodes to crosslink the third photocurable polymer material in the third vias prior to the step of attaching.   
     
     
         4 . The method of  claim 3 , further comprising forming the first vias, the second vias, and the third vias in a single via formation operation. 
     
     
         5 . The method of  claim 4 , wherein the matrix material, including the first vias, the second vias, and the third vias is formed by injection molding, and wherein the matrix material comprises a polymer material. 
     
     
         6 . The method of  claim 3 , wherein the matrix material comprises a positive-tone photosensitive polymer formed over a first substrate. 
     
     
         7 . The method of  claim 6 , further comprising:
 selectively illuminating first portions, second portions, and third portions of the positive-tone photosensitive polymer with the respective first, second and third light emitting diodes of the array of light emitting diodes to form un-crosslinked polymer material respectively in the first portions, the second portions, and the third portions of the matrix material; and   removing the un-crosslinked polymer material respectively in the first portions, the second portions, and the third portions to form the first vias, the second vias, and the third vias.   
     
     
         8 . The method of  claim 3 , wherein:
 the step of depositing in the first vias in the matrix material the first photocurable quantum dot ink comprises selectively depositing the first photocurable quantum dot ink only in the first vias;   the step of depositing in the second vias in the matrix material the second photocurable quantum dot ink comprises selectively depositing the second photocurable quantum dot ink only in the second vias after the step of illuminating the first photocurable quantum dot ink; and   the step of depositing in the third vias in the matrix material the third photocurable quantum dot ink comprises selectively depositing the third photocurable quantum dot ink only in the third vias after the step of illuminating the second photocurable quantum dot ink.   
     
     
         9 . The method of  claim 3 , wherein:
 the step of depositing in the first vias in the matrix material the first photocurable quantum dot ink comprises non-selectively depositing the first photocurable quantum dot ink in the first, the second and the third vias, followed by removing un-crosslinked portions of the first photocurable quantum dot ink from the second and the third vias after the step of illuminating the first photocurable quantum dot ink;   the step of depositing in the second vias in the matrix material the second photocurable quantum dot ink comprises non-selectively depositing the second photocurable quantum dot ink in the second and the third vias, followed by removing un-crosslinked portions of the second photocurable quantum dot ink from the third vias after the step of illuminating the second photocurable quantum dot ink; and   the step of depositing in the third vias in the matrix material the third photocurable quantum dot ink comprises depositing the third photocurable quantum dot ink in the third vias, after the step of illuminating the third photocurable quantum dot ink.   
     
     
         10 . The method of  claim 1 , further comprising forming a protective layer over the color conversion device. 
     
     
         11 . The method of  claim 1 , wherein the free standing support containing the first and the second quantum dots comprises a color conversion device. 
     
     
         12 . The method of  claim 11 , further comprising:
 forming protrusions in a mating surface of at least one of the color conversion device and the array of light emitting diodes;   forming recesses in the mating surface of at least one of the color conversion device and the array of light emitting diodes; and   attaching the color conversion device to the array of light emitting diodes such that the protrusions are inserted into the respective grooves to form an interlocking pattern to align the color conversion device and the array of light emitting diodes.   
     
     
         13 . The method of  claim 11 , wherein:
 the first and the second of vias are partially filled with the crosslinked first and second photocurable polymer material to leave grooves; and   the array of LEDs comprise protrusions which are inserted into the respective grooves to form an interlocking pattern to align the color conversion device and the array of light emitting diodes.   
     
     
         14 . A method of forming a light emitting device, comprising:
 providing a plurality of light emitting diodes on a substrate such that the plurality of light emitting diodes is configured to emit blue light or ultraviolet radiation incident photons;   providing a color conversion device comprising a color conversion material formed in a plurality of vias in a matrix material;   positioning the color conversion device relative to the plurality of light emitting diodes such that each of the plurality of vias is located over a corresponding one of the plurality of light emitting diodes, wherein the color conversion material in each of the plurality of vias is configured to absorb the incident photons from the corresponding one of the plurality of light emitting diodes and to generate converted photons having a longer peak wavelength than a peak wavelength of the incident photons; and   adjusting a position of the color conversion device relative to the plurality of light emitting diodes to thereby maximize an intensity of the converted photons having the longer peak wavelength.   
     
     
         15 . The method of  claim 14 , wherein the step of adjusting the position of the color conversion device relative to the plurality of light emitting diodes further comprises:
 determining a first maximum intensity of converted photons as a first function of position of the color conversion device relative to the plurality of light emitting diodes along a first direction in a two dimensional plane that is parallel to an interface between the color conversion device and the substrate;   determining a second maximum intensity of converted photons as a second function of position of the color conversion device relative to the plurality of light emitting diodes along a second direction in the two dimensional plane that is parallel to the interface between the color conversion device and the substrate; and   determining a maximum intensity of converted photons as a function of an orientation angle of the color conversion device relative to the plurality of light emitting diodes in a two dimensional plane that is parallel to an interface between the color conversion device and the substrate.   
     
     
         16 . A light emitting device, comprising:
 a substrate:   a plurality of light emitting diodes located on the substrate and configured to emit blue or ultraviolet radiation incident photons; and   a color conversion device comprising a color conversion material located in a plurality of vias in a matrix material,   wherein each of the plurality of vias is located over a corresponding one of the plurality of light emitting diodes such that the color conversion material in each of the plurality of vias is configured to absorb the incident photons from the corresponding one of the plurality of light emitting diodes and to generate converted photons having a longer peak wavelength than a peak wavelength of the incident photons, and   wherein the color conversion device is a free standing structure that is attached over the plurality of light emitting diodes.   
     
     
         17 . The light emitting device of  claim 16 , wherein:
 each of the plurality of light emitting diodes comprises a width of 10 microns or less and adjacent light emitting diodes are separated by a distance of 1 micron or less;   the color conversion material comprises quantum dots;   the quantum dots are configured to absorb the incident photons and to emit the converted photons having a color that is one of red, green, or blue; and   the plurality of vias in the matrix material are arranged in an ordered array of pixels with each pixel comprising a red subpixel, a green subpixel, and a blue subpixel such that the color conversion material in respective subpixels is configured to respectively generate red, green, and blue converted photons.   
     
     
         18 . The light emitting device of  claim 16 , wherein:
 at least one of the color conversion device and plurality of light emitting diodes contains protrusions in a mating surface;   at least one of the color conversion device and plurality of light emitting diodes contains grooves in the mating surface; and   the protrusions are inserted into the respective grooves to form an interlocking pattern to align the color conversion device and the plurality of light emitting diodes.   
     
     
         19 . The light emitting device of  claim 16 , wherein:
 the plurality of vias are partially filled with the color conversion material to leave grooves; and   the plurality of LEDs comprise protrusions which are inserted into the respective grooves to form an interlocking pattern to align the color conversion device and the plurality of light emitting diodes.   
     
     
         20 . The light emitting device of  claim 16 , wherein the color conversion device and plurality of light emitting diodes are held together by at least one of an adhesive or a mechanical attachment feature.